Plasma neurofilament light and its association with all-cause mortality risk among urban middle-aged men and women

BACKGROUND: Neurofilament light chain (NfL) is released into the blood during neuronal damage. NfL is linked to mortality in neurological disorders, remaining unexplored in population studies. We investigated whether initial (v(1)) and annualized change (δ) in plasma NfL can predict all-cause mortality in middle-aged dementia-free urban adults. METHODS: Longitudinal data were from 694 participants in the Healthy Aging in Neighborhoods of Diversity Across the Life Span study (HANDLS, mean age(v1): 47.8 years, 42% male, 55.8% African American). Plasma NfL was measured prospectively at three visits. Analyses included Cox proportional hazards models for all-cause mortality risk and 4-way decomposition testing for interaction and mediation. RESULTS: Unlike men, women exhibited a direct association between δNfL (above vs. below median) and all-cause mortality risk in both the minimally (HR = 3.91, 95% CI 1.10–13.9, p = 0.036) and fully adjusted models (HR = 4.92, 95% CI 1.26–19.2, p = 0.022), and for δNfL (per unit increase) in the full model (HR = 1.65, 95% CI 1.04–2.61, p = 0.034). In both models, and among women, 1 standard deviation of NfL(v1) was associated with an increased all-cause mortality risk (reduced model: HR = 2.01, 95% CI 1.24–3.25, p = 0.005; full model: HR = 1.75, 95% CI 1.02–2.98, p = 0.041). Only few interactions were detected for cardio-metabolic risk factors. Notably, NfL(v1) was shown to be a better prognostic indicator at normal hsCRP values among women, while HbA1c and δNfL interacted synergistically to determine mortality risk, overall. CONCLUSIONS: These findings indicate that plasma NfL levels at baseline and over time can predict all-cause mortality in women and interacts with hsCRP and HbA1c to predict that risk. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12916-022-02425-x.